The present invention pertains to a device for guiding a workpiece in a sewing machine which includes two superposed passages in each of which a layer of fabric is adapted to travel. These passages serve to align the edges of the two layers of fabric prior to joining said edges by means of an assembly seam.
In known guiding devices of the above mentioned type the superposed passages are commonly formed by horizontal laminae between which a limiting element is inserted. The height of the limiting element corresponds to the thickness of each layer to be assembled and the guiding surface thereof is located at a predetermined distance within the passage so as to control the distance of the assembly seam from the edges being joined.
Each limiting element within its respective passage is generally formed by a small block of desired shape or can be formed by a series of pegs which extend through the laminae and whose successive arrangement forms the above mentioned guiding surface.
The distance of the guiding surface or so-called vertical wall of the limiting element from the axis of stitching can be varied at the assembly stage in order to control the distance at which the seam must be formed from the edge of the layers of fabric. Once this distance has been fixed, it remains unchanged during the stitching operation.
Known guiding devices have been found to be completely inadequate in automatic stitching operations when it is necessary to align layers having portions thereof of different widths while joining them by means of an assembly seam.
The problem is particularly felt where it is necessary to provide, for exammple, an inner assembly seam on the leg portions of trousers wherein a portion of one layer of the workpiece is of greater width than the other and which must be brought into alignment, one with the other. The alignment and joining of layers of fabric in the manner described above serves to provide a configuration to the article of clothing being formed which corresponds to the actual shape of the body of the person who will wear said article.
An object of the invention is to provide a guiding device for a workpiece which is capable of displacing the edge of at least one of the layers of fabric with respect to the other during the formation of the seam so that the seam will not be parallel to said displaced edge.